EP2051028B1 - Refrigerant loading method for refrigeration device using carbon dioxide as refrigerant - Google Patents
Refrigerant loading method for refrigeration device using carbon dioxide as refrigerant Download PDFInfo
- Publication number
- EP2051028B1 EP2051028B1 EP07790941.4A EP07790941A EP2051028B1 EP 2051028 B1 EP2051028 B1 EP 2051028B1 EP 07790941 A EP07790941 A EP 07790941A EP 2051028 B1 EP2051028 B1 EP 2051028B1
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- European Patent Office
- Prior art keywords
- refrigerant
- charging
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- intended
- container
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- 239000003507 refrigerant Substances 0.000 title claims description 400
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims description 161
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims description 103
- 238000005057 refrigeration Methods 0.000 title claims description 90
- 239000001569 carbon dioxide Substances 0.000 title claims description 52
- 238000011068 loading method Methods 0.000 title 1
- 238000000034 method Methods 0.000 claims description 64
- 238000010438 heat treatment Methods 0.000 claims description 31
- 238000001816 cooling Methods 0.000 claims description 20
- 239000012071 phase Substances 0.000 claims description 15
- 239000007791 liquid phase Substances 0.000 claims description 13
- 239000007787 solid Substances 0.000 description 37
- 238000004519 manufacturing process Methods 0.000 description 23
- 238000004378 air conditioning Methods 0.000 description 20
- 239000003570 air Substances 0.000 description 15
- 238000010586 diagram Methods 0.000 description 7
- 235000011089 carbon dioxide Nutrition 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 239000013256 coordination polymer Substances 0.000 description 4
- 238000009434 installation Methods 0.000 description 4
- 238000011835 investigation Methods 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000000498 cooling water Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000012080 ambient air Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000000153 supplemental effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B45/00—Arrangements for charging or discharging refrigerant
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
- F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B13/00—Compression machines, plants or systems, with reversible cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2309/00—Gas cycle refrigeration machines
- F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
- F25B2309/061—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide with cycle highest pressure above the supercritical pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
- F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
- F25B2313/02741—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using one four-way valve
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2345/00—Details for charging or discharging refrigerants; Service stations therefor
- F25B2345/001—Charging refrigerant to a cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/01—Heaters
Definitions
- the present invention relates to a refrigerant charging method for a refrigeration device in which carbon dioxide is used as a refrigerant, and particularly to a refrigerant charging method performed when the refrigerant is charged in the refrigeration device on-site after an indoor unit and an outdoor unit have been connected by interconnecting piping.
- CFCs Fluorocarbons
- Patent Document 1 Fluorocarbons
- US 2006/0101835 A1 discloses a charging system for charging a refrigeration system of a vehicle.
- 2005/132729 A1 discloses a refrigerant charging method according to the preamble of claim 1 and a refrigerant charging method according to the preamble of claim 4.
- the system includes a controller of a refrigerant source, at least one line fluidly connecting the refrigerant source to the refrigeration system; a control valve disposed to control flow of the refrigerant from the refrigerant source to the refrigeration system; and an efficiency sensor for measuring the efficiency of the refrigeration system.
- JP 11-132602 A discloses a refrigerant sealing device in which a valve of a tank is opened to introduce carbon dioxide into a sealed space. Thereby, a thermostatic room contains a pressure control valve and maintains an atmospheric temperature at a prescribed temperature of approximately 40°C above a critical temperature of carbon dioxide.
- Patent document 1 Japanese Laid-open Patent Publication No. 2001-74342 .
- Hot-water-supplying devices that are already on the market, the task of charging refrigerant (carbon dioxide) into the refrigeration cycle is performed at a manufacturing plant belonging to the manufacturer.
- Hot-water-supplying devices in which carbon dioxide is used as a refrigerant are not regarded to be in widespread use at present, and there is little demand to reduce the time required to perform the refrigerant charging task to facilitate mass production, even in manufacturing plants.
- interconnecting refrigerant piping for connecting the indoor and outdoor units is fitted on-site in the building in which the air conditioners are to be installed, and often the refrigerant charging task is performed on-site.
- additional refrigerant charging tasks will be performed on site, depending on the length of the interconnecting refrigerant piping that has been fitted on-site, as well as other factors.
- on-site refrigerant charging tasks a method is adopted in which the space inside the piping is evacuated using a vacuum pump or the like, and a refrigerant is delivered from a cylinder into the piping.
- An object of the present invention is to provide a refrigerant charging method for a refrigeration device in which carbon dioxide is used as a refrigerant, wherein it is possible to reduce the time required for refrigerant charging and the time between refrigerant charging and recommencing operation.
- a refrigerant charging method is a refrigerant charging method used when a refrigeration device having an indoor unit and an outdoor unit and having carbon dioxide used as a refrigerant is installed on-site, the indoor unit and the outdoor unit are connected using interconnecting piping, and the refrigerant is subsequently charged on-site into the refrigeration device.
- the refrigerant charging method comprises a connecting step and a refrigerant charging step.
- a container containing the refrigerant is connected to a space in the refrigeration device that is intended to be charged by refrigerant, heating means being interposed therebetween.
- the refrigerant is moved from the container to the intended charging space that is substantially in a vacuum state, via the heating means.
- the refrigerant that has exited the container is heated by the heating means so that a specific enthalpy of the refrigerant when entering the intended charging space will be 430 kJ/kg or higher.
- Refrigeration devices such as a hot-water-supplying device having a refrigeration cycle in which a carbon dioxide refrigerant is used are currently charged with the refrigerant at a manufacturing plant or another production site belonging to a manufacturer.
- refrigeration devices such as office air conditioners are not charged with carbon dioxide refrigerant at the locations at which the devices are installed.
- carbon dioxide refrigerants are only widely used in refrigeration devices that are not charged at the installation location; the only refrigeration devices sold commercially have been completely charged with the refrigerant at the manufacturing site.
- the refrigerant charging task needs to be optimized and efficient when the use of a carbon dioxide refrigerant is considered for application in office air conditioners or other refrigeration devices where it is common for interconnecting refrigerant piping for connecting indoor and outdoor units to be fitted in the buildings where the device is installed, and charging of the refrigerant to be performed on-site.
- the present inventors conducted a variety of investigations into charging refrigeration devices with a carbon dioxide refrigerant.
- the refrigerant is to be charged into the intended charging space of a refrigeration device having carbon dioxide as a refrigerant, and the temperature of a cylinder for discharging and supplying the refrigerant exceeds 31°C, the carbon dioxide refrigerant inside the cylinder will reach a supercritical state.
- the refrigerant starts to be supplied from the cylinder into the intended charging space, which is substantially in a vacuum state, then in some instances the amount of heat held by the refrigerant will cause the pressure to decrease sharply, whereby the refrigerant will change into a "dry ice” state (solid state).
- the specific enthalpy of the refrigerant when entering the intended charging space is less than 430 kJ/kg, an abrupt drop in the pressure can cause the refrigerant to change to a solid state. If the refrigerant changes to a solid state while in the intended charging space, the trailing refrigerant flowing into the space will be obstructed by the solidified refrigerant and the time until the charging is completed will increase, or more time will elapse after charging until the operation can recommence (until the solid state refrigerant dissolves).
- heating means is provided between a refrigerant container and the space intended to be charged by the refrigerant, and the refrigerant is heated using the heating means, causing the specific enthalpy of the refrigerant to be 430 kJ/kg or higher when it enters the intended charging space.
- a refrigerant charging method is a refrigerant charging method for a refrigeration device in which carbon dioxide is used as a refrigerant, the method comprising a connecting step and a refrigerant charging step.
- a container containing the refrigerant is connected to a space in the refrigeration device that is intended to be charged by refrigerant, heating means being interposed therebetween.
- the refrigerant charging step the refrigerant is moved from the container to the intended charging space that is substantially in a vacuum state, via the heating means.
- the refrigerant that has exited the container is heated by the heating means so that a specific enthalpy of the refrigerant when entering the intended charging space will be 430 kJ/kg or higher.
- Refrigeration devices such as a hot-water-supplying device having a refrigeration cycle in which a carbon dioxide refrigerant is used are currently charged with the refrigerant at a manufacturing plant belonging to a manufacturer.
- refrigeration devices such as office air conditioners are not charged with carbon dioxide refrigerant at the locations at which the devices are installed.
- carbon dioxide refrigerants are only widely used in refrigeration devices that are not charged at the installation location; the only refrigeration devices sold commercially have been completely charged with the refrigerant at the manufacturing site.
- hot-water-supplying devices and other refrigeration devices having carbon dioxide refrigerants are not mass-produced, and there is little demand to reduce the time required to perform the refrigerant charging task to facilitate mass production.
- the refrigerant charging task needs to be optimized and efficient in instances such as when the use of a carbon dioxide refrigerant is considered for application in commercial air conditioners or other refrigeration devices where it is common for interconnecting refrigerant piping for connecting indoor and outdoor units to be fitted in the buildings where the device is installed, and charging of the refrigerant to be performed on-site; or when refrigeration devices are mass-produced at a production site.
- the present inventors conducted a variety of investigations into charging refrigeration devices with a carbon dioxide refrigerant.
- the refrigerant when the refrigerant is to be charged into the intended charging space of a refrigeration device having carbon dioxide as a refrigerant, in some instances the amount of heat held by the refrigerant will cause the pressure to decrease sharply, whereby the refrigerant will change into a "dry ice" state (solid state).
- a "dry ice" state solid state
- the specific enthalpy of the refrigerant when entering the intended charging space is less than 430 kJ/kg, an abrupt drop in the pressure can cause the refrigerant to change to a solid state.
- the trailing refrigerant flowing into the space will be obstructed by the solidified refrigerant and the time until the charging is completed will increase, or more time will elapse after charging until the operation can recommence (until the solid state refrigerant dissolves).
- heating means is provided between a refrigerant container and the space intended to be charged by the refrigerant, and the refrigerant is heated using the heating means, causing the specific enthalpy of the refrigerant to be 430 kJ/kg or higher when it enters the intended charging space.
- the heating means is a hose or piping connecting a cylinder or other container containing high-pressure refrigerant to a space intended to be charged by the refrigerant in refrigerant piping or another part of a refrigeration device.
- the heating means may be piping having an attached heater, or an uninsulated hose or piping through which the heat of the outside air is transferred to the refrigerant.
- the refrigerant charging method is the method of the first and second aspects, wherein in the refrigerant charging step, the refrigerant that has exited the container is heated by the heating means so that the temperature and pressure of the refrigerant when entering the intended charging space will be values that exceed those on a boundary line passing through points 1 to 5.
- the first point is the point at a temperature of 0°C and a pressure of 3.49 MPa
- the second point is the point at a temperature of 10°C and a pressure of 4.24 MPa
- the third point is the point at a temperature of 20°C and a pressure of 5.07 MPa
- the fourth point is the point at a temperature of 30°C and a pressure of 6.00 MPa
- the fifth point is the point at a temperature of 40°C and a pressure of 7.06 MPa.
- the refrigerant that has exited the container is heated by the heating means so that the temperature and pressure of the refrigerant when entering the intended charging space will be values that exceed those on the boundary line passing through points 1 to 5. Therefore, the specific enthalpy of the refrigerant when entering the intended charging space will be 430 kJ/kg or higher, and the refrigerant will not change to a solid state while in the space targeted for charging by refrigerant.
- a refrigerant charging method is a refrigerant charging method used when a refrigeration device having an indoor unit and an outdoor unit and having carbon dioxide used as a refrigerant is installed on-site, the indoor unit and the outdoor unit are connected using interconnecting piping, and the refrigerant is subsequently charged on-site into the refrigeration device.
- the refrigerant charging method comprises a cooling step and a refrigerant charging step.
- a container that contains the refrigerant and supplies the refrigerant to the space in the refrigeration device intended to be charged by the refrigerant is cooled to 31°C or below.
- the refrigerant is moved to the intended charging space that is substantially in a vacuum state from the container that has reached 31°C or below via the cooling step.
- the refrigerant charging step first, the refrigerant that is in a gas phase within the container is moved into the intended charging space, whereupon the refrigerant that is in a liquid phase within the container is moved into intended charging space.
- Refrigeration devices such as a hot-water-supplying device having a refrigeration cycle in which a carbon dioxide refrigerant is used are currently charged with the refrigerant at a manufacturing plant belonging to a manufacturer.
- refrigeration devices such as office air conditioners are not charged with carbon dioxide refrigerant at the locations at which the devices are installed.
- carbon dioxide refrigerants are only widely used in refrigeration devices that are not charged at the installation location; the only refrigeration devices sold commercially have been completely charged with the refrigerant at the manufacturing site.
- the refrigerant charging task needs to be optimized and efficient when the use of a carbon dioxide refrigerant is considered for application in refrigeration devices such as commercial air conditioners where it is common for interconnecting refrigerant piping for connecting indoor and outdoor units to be fitted in the buildings where the device is installed, and charging of the refrigerant to be performed on-site.
- the present inventors conducted a variety of investigations into charging refrigeration devices with a carbon dioxide refrigerant.
- the trailing refrigerant flowing into the space will be obstructed by the solidified refrigerant and the time until the charging is completed will increase, or more time will elapse after charging until the operation can recommence (until the solid state refrigerant dissolves).
- a cooling step is provided before the refrigerant charging step.
- a container that supplies the refrigerant to the space in the refrigeration device intended to be charged by the refrigerant is cooled to 31°C or below.
- the refrigerant that is in a gas phase inside the container will first be caused to move into the space intended to be charged by the refrigerant; therefore, it will be substantially impossible for the refrigerant to change to the solid state even if the intended charging space is in a vacuum state and the refrigerant experiences an abrupt drop in pressure.
- Refrigerant that is in a liquid phase will similarly not change to a solid state in the intended charging space because the refrigerant that is in a liquid phase inside the cylinder will enter the intended charging space after the refrigerant that is in a gas phase inside the container has entered the intended charging space and the pressure therein has risen to some extent.
- the refrigerant charging method of the fourth aspect it is possible to prevent the incidence of circumstances under which refrigerant that has entered the intended charging space from the container changes into a solid state during the charging process, and to minimize the incidence of faults related to, e.g., the solid-state refrigerant becoming an obstruction, as well as an increase in the charging time or the time following refrigerant charging until operation recommences.
- the refrigerant charging method is a refrigerant charging method for a refrigeration device in which carbon dioxide is used as a refrigerant, and comprises a cooling step and a refrigerant charging step.
- a container that contains the refrigerant and supplies the refrigerant to a space in the refrigeration device intended to be charged by the refrigerant is cooled to 31°C or below.
- the refrigerant charging step the refrigerant is moved to the intended charging space that is substantially in a vacuum state from the container that has reached 31°C or below via the cooling step.
- the refrigerant charging step first, the refrigerant that is in a gas phase within the container is moved into the intended charging space, whereupon the refrigerant that is in a liquid phase within the container is moved into the intended charging space.
- Refrigeration devices such as a hot-water-supplying device having a refrigeration cycle in which a carbon dioxide refrigerant is used are currently charged with the refrigerant at a manufacturing plant or another production site belonging to a manufacturer.
- refrigeration devices such as office air conditioners are not charged with carbon dioxide refrigerant at the locations at which the devices are installed.
- carbon dioxide refrigerants are only widely used in refrigeration devices that are not charged at the installation location; the only refrigeration devices sold commercially have been completely charged with the refrigerant at the manufacturing site.
- refrigeration devices having carbon dioxide refrigerants such as hot-water-supplying devices are not mass-produced, and there is little demand to reduce the time required to perform the refrigerant charging task to facilitate mass production.
- the refrigerant charging task needs to be optimized and efficient in such instances as when the use of a carbon dioxide refrigerant is considered for application in office air conditioners or other refrigeration devices where it is common for interconnecting refrigerant piping for connecting indoor and outdoor units to be fitted in the buildings where the device is installed, and charging of the refrigerant to be performed on-site; or when refrigeration devices are mass-produced at a production site.
- the present inventors conducted a variety of investigations into charging refrigeration devices with a carbon dioxide refrigerant.
- the trailing refrigerant flowing into the intended charging space will be obstructed by the solidified refrigerant and the time until the charging is completed will increase, or more time will elapse after charging until the operation can recommence (until the solid state refrigerant dissolves).
- a cooling step is provided before the refrigerant charging step.
- a container that supplies the refrigerant to the space in the refrigeration device intended to be charged by the refrigerant is cooled to 31°C or below.
- the refrigerant that is in a gas phase inside the container will first be caused to move into the space intended to be charged by the refrigerant; therefore, it will be substantially impossible for the refrigerant to change to the solid state even if the intended charging space is in a vacuum state and the refrigerant experiences an abrupt drop in pressure.
- Refrigerant that is in a liquid phase will similarly not change to a solid state in the space intended to be charged by the refrigerant because the refrigerant that is in a liquid phase inside the cylinder will enter the intended charging space after the refrigerant that is in a gas phase inside the container has entered the intended charging space and the pressure therein has risen to some extent.
- the refrigerant charging method of the fifth aspect it is possible to prevent the incidence of circumstances under which refrigerant that has entered the intended charging space from the container changes into a solid state during the charging process, and to minimize the incidence of faults related to, e.g., the solid-state refrigerant becoming an obstruction, as well as an increase in the charging time or the time following refrigerant charging until operation recommences.
- the container may be cooled using cooling water, or, when the surrounding atmospheric temperature is low, the container may be cooled using ambient air (including the time until the container reaches 31°C or lower)
- the refrigerant charging method of the first to third aspects even if the refrigerant inside the high-temperature cylinder is in a supercritical state, it is possible to prevent the refrigerant changing into a solid state during the charging process due to the pressure sharply decreasing, and to minimize the incidence of faults related to, e.g., the solid-state refrigerant becoming an obstruction, as well as an increase in the charging time or the time following refrigerant charging until operation recommences.
- the refrigerant charging method of the fourth and fifth aspects it is possible to prevent the incidence of circumstances under which refrigerant that has entered the intended charging space from the container changes into a solid state during the charging process, and to minimize the incidence of faults related to, e.g., the solid-state refrigerant becoming an obstruction, as well as an increase in the charging time or the time following refrigerant charging until operation recommences.
- the refrigerant charging method according to the present invention is a method for supplying the refrigerant from a cylinder or another container in which the refrigerant is contained to a space intended to be charged by the refrigerant within the refrigeration cycle, and for efficiently charging the intended charging space with the necessary amount of refrigerant.
- a brief description shall be provided of the refrigeration cycle to be charged with refrigerant using the refrigerant charging method, after which a description shall be provided of a refrigerant charging method according to a first embodiment and a refrigerant charging method according to a second embodiment.
- FIG. 1 is drawing of a refrigeration cycle of an air conditioning device 10 in which carbon dioxide is used as a refrigerant (hereinafter referred to as CO 2 refrigerant).
- the air conditioning device 10 is a multiple-unit air conditioning device installed in an office building or similar structure, and is used for cooling or heating a plurality of spaces, the device having a plurality of indoor units 50 linked to a single outdoor unit 20.
- the air conditioning device 10 comprises the outdoor unit 20, the plurality of indoor units 50, and interconnecting refrigerant piping 6, 7 for connecting the units 20, 50.
- the outdoor unit 20 has a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an outdoor expansion valve 24, closing valves 25, 26, and other components; and is brought into the building in a state of having been charged with CO 2 refrigerant in advance.
- Each of the indoor units 50 has an indoor expansion valve 51 and an indoor heat exchanger 52, is installed in the ceiling or other region of each open space (rooms or the like) inside the building, and is connected to the outdoor unit via the interconnecting refrigerant piping 6, 7, which are fitted on-site. Fitting the piping on-site to the outdoor unit 20 and the indoor units 50 brought into the building thus forms a single refrigeration cycle.
- the refrigeration cycle of the air conditioning device 10 is a closed circuit in which the compressor 21, the four-way switching valve 22, the outdoor heat exchanger 23, the outdoor expansion valve 24, each indoor expansion valve 51, and each indoor heat exchanger 52 are linked by refrigerant piping that includes the interconnecting refrigerant piping 6, 7.
- refrigerant piping that includes the interconnecting refrigerant piping 6, 7.
- the air conditioning device 10 reaches a state in which heat exchange is performed between the CO 2 refrigerant flowing through the indoor heat exchangers 52 of the indoor units 50, and the air inside the rooms, whereby an air conditioning operation for cooling or heating the spaces inside the building can be performed.
- the four-way switching valve 22 in the air conditioning device 10 is used to switch the direction in which the refrigerant flows, thereby making it possible to switch between a heating operation and a cooling operation.
- the outdoor heat exchanger 23 becomes a gas cooler, and the indoor heat exchangers 52 become evaporators.
- the outdoor heat exchanger 23 becomes an evaporator, and the indoor heat exchangers 52 become gas coolers.
- point A is an inlet side of the compressor 21 during the heating operation
- point B is a discharge side of the compressor 21 during the heating operation
- Point C is a refrigerant outlet of the indoor heat exchangers 52 during the heating operation
- point D is a refrigerant entrance of the outdoor heat exchanger 23 during the heating operation.
- FIG. 2 is a diagram used to express a pressure-enthalpy state of the CO 2 refrigerant in a simplified manner, wherein the vertical axis shows the pressure and the horizontal axis shows the enthalpy.
- Tcp is a constant temperature line that passes through a critical point CP.
- the CO 2 refrigerant enters a supercritical state, wherein the CO 2 refrigerant becomes a fluid simultaneously exhibiting diffusibility, which is a characteristic of a gas, and solubility, which is a characteristic of a liquid.
- the air conditioning device 10 operates using a refrigeration cycle that includes the supercritical state, as shown by the bold line in FIG. 2 .
- the CO 2 refrigerant is compressed by the compressor 21 up to a pressure that exceeds the critical pressure, cooled to a liquid by the indoor heat exchanger 52, decompressed at the outdoor expansion valve 24, evaporated in the outdoor heat exchanger 23, becomes a gas, and is once more drawn into the compressor 21.
- the outdoor unit 20 and the indoor units 50 are connected using the interconnecting refrigerant piping 6, 7, which is fitted on-site. After a single closed refrigeration cycle has been formed therefrom, the refrigerant charging task is performed.
- the interior of the indoor units 50 and the interconnecting refrigerant piping 6, 7 is evacuated (brought to extremely low pressure) using a vacuum pump or the like (not shown).
- a cylinder 81 containing CO 2 refrigerant is connected to a charge port installed near the closing valve 26 of the outdoor unit 20.
- a heater 83 is attached to the piping connecting the cylinder 81 and the charge port a heater 83 for heating the piping and the CO 2 refrigerant that flows through the interior thereof.
- the heater 83 is activated so that the specific enthalpy of the CO 2 refrigerant having entered the interconnecting refrigerant piping 7 from the charge port will reach 430 kJ/kg or higher, and refrigerant charging will be performed. Specifically, the heater 83 is activated so that the temperature and pressure of the CO 2 refrigerant having entered the interconnecting refrigerant piping 7 will fall in the area on the higher [value] side of the line connecting the five points PI to P5 shown in FIG. 4 .
- Point PI is the point at a temperature of 0°C and a pressure of 3.49 MPa
- point 2 is the point at a temperature of 10°C and a pressure of 4.24 MPa
- point 3 is the point at a temperature of 20°C and a pressure of 5.07 MPa
- point 4 is the point at a temperature of 30°C and a pressure of 6.00 MPa
- point 5 is the point at a temperature of 40°C and a pressure of 7.06 MPa.
- the CO 2 refrigerant that has exited the cylinder 81 is heated by the heater 83 so that the specific enthalpy of the CO 2 refrigerant will reach 430 kJ/kg or higher.
- the CO 2 refrigerant will not change to a solid state, because as long as the specific enthalpy is 430 kJ/kg or higher, carbon dioxide will not change to a solid (see FIG. 4 ).
- the specific enthalpy of the CO 2 refrigerant is brought to 430 kJ/kg or higher at the time the CO 2 refrigerant enters the evacuated space intended to be charged (the interior space of the indoor units 50 and the interconnecting refrigerant piping 6, 7), there will be no incidence of faults related to, e.g., the CO 2 refrigerant in the interconnecting refrigerant piping 7 changing to a solid near the charge port and obstructing the flow of the trailing CO 2 refrigerant, or long periods of time elapsing after charging until the air conditioning device 10 can be operated.
- a heater 83 is attached to the piping between the cylinder 81 and the charge port; however, in place of installing the heater 83, it is possible to adopt a method involving lengthening the piping between the cylinder 81 and the charge port. It is possible for the long piping between the cylinder 81 and the charge port to not have an insulation material or the like wrapped therearound, and for heat in the air surrounding to be used to heat the CO 2 refrigerant flowing through the piping.
- the outdoor unit 20 and the indoor units 50 are connected using the interconnecting refrigerant piping 6, 7, which is fitted on-site. After a single closed refrigeration cycle has been formed therefrom, the refrigerant charging task is performed. A description will be given with reference to FIG. 3 ; however, in a case in which the refrigerant charging method according to a second embodiment is employed, the heater 83 shown in FIG. 3 will be unnecessary.
- the interiors of the indoor units 50 and the interconnecting refrigerant piping 6,7 are evacuated (brought to extremely low pressure) using a vacuum pump or the like (not shown).
- a cylinder 81 containing CO 2 refrigerant is connected to a charge port installed near the closing valve 26 of the outdoor unit 20.
- the cylinder 81 is cooled so as to bring the temperature of the CO 2 refrigerant inside the cylinder 81 to 31°C or below.
- the cylinder 81 is cooled using cooling water or another medium (not shown).
- the CO 2 refrigerant in a gas phase (gaseous state) within the cylinder 81 is discharged and supplied into the space intended to be charged by the refrigerant (the space within the indoor unit 50 and the interconnecting refrigerant piping 6, 7).
- the CO 2 refrigerant in a liquid phase (liquid state) within the cylinder 81 is discharged and supplied into the intended charging space.
- the cylinder 81 is cooled to 31°C or below, before refrigerant charging is performed.
- the refrigerant inside the cylinder 81 will not reach the supercritical state, and will be in a liquid phase or gas phase.
- the CO 2 refrigerant that is in a gas phase inside the container 81 will first be caused to move into the space intended to be charged by the refrigerant; therefore, it will be substantially impossible for the refrigerant to change to the solid state even if the intended charging space is in a vacuum state and the CO 2 refrigerant experiences an abrupt drop in pressure.
- CO 2 refrigerant that is in a liquid phase will similarly not change to a solid state in the space intended to be charged by the refrigerant because the refrigerant that is in a liquid phase inside the cylinder 81 will enter the intended charging space after the CO 2 refrigerant that is in a gas phase inside the cylinder 81 has entered the space and the pressure therein has risen to some extent.
- the refrigerant charging method according to the second embodiment there will be substantially no incidence of any fault related to, e.g., the CO 2 refrigerant changing to a solid near the charge port and obstructing the flow of the trailing CO 2 refrigerant, or long periods of time elapsing after charging until the air conditioning device 10 can be operated.
- any fault related to e.g., the CO 2 refrigerant changing to a solid near the charge port and obstructing the flow of the trailing CO 2 refrigerant, or long periods of time elapsing after charging until the air conditioning device 10 can be operated.
- the temperature of the CO 2 refrigerant inside the cylinder 81 decreases, and as long as the CO 2 refrigerant that is in a gas phase discharges first among the liquid- and gas-phase CO 2 refrigerant into the space intended to be charged by the refrigerant, there will be substantially no incidence of any fault related to, e.g., the CO 2 refrigerant changing to a solid near the charge port and obstructing the flow of the trailing CO 2 refrigerant, or long periods of time elapsing after charging until the air conditioning device 10 can be operated.
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Description
- The present invention relates to a refrigerant charging method for a refrigeration device in which carbon dioxide is used as a refrigerant, and particularly to a refrigerant charging method performed when the refrigerant is charged in the refrigeration device on-site after an indoor unit and an outdoor unit have been connected by interconnecting piping.
- Fluorocarbons (CFCs) have conventionally been the main refrigerant used in refrigeration devices; however, developments have been made over the past several years in regard to technologies in which carbon dioxide is used as a refrigerant. Carbon dioxide refrigeration cycles, such as disclosed in
Patent Document 1, are widely known in the field of air conditioners used in automotive vehicles, and commercial products in which carbon dioxide is used as a refrigerant are used in the field of hot-water-supplying devices. - However, products used in the field of air conditioners for domestic or office use are currently only in the developmental stage, and are not yet ready to be brought to market. In this context,
US 2006/0101835 A1 discloses a charging system for charging a refrigeration system of a vehicle.2005/132729 A1 discloses a refrigerant charging method according to the preamble ofclaim 1 and a refrigerant charging method according to the preamble of claim 4. The system includes a controller of a refrigerant source, at least one line fluidly connecting the refrigerant source to the refrigeration system; a control valve disposed to control flow of the refrigerant from the refrigerant source to the refrigeration system; and an efficiency sensor for measuring the efficiency of the refrigeration system. The controller operates to cause the charging system to input into the refrigeration system a predetermined amount of refrigerant less than a recommended refrigerant charge amount; measure a baseline efficiency of the refrigeration system, input a supplemental amount of refrigerant into the refrigeration system, measure an adjusted efficiency of the refrigeration system, and compare the measured adjusted efficiency to the baseline efficiency using the controller. Further,JP 11-132602 A - (Patent document 1)
Japanese Laid-open Patent Publication No.2001-74342 - In hot-water-supplying devices that are already on the market, the task of charging refrigerant (carbon dioxide) into the refrigeration cycle is performed at a manufacturing plant belonging to the manufacturer. Hot-water-supplying devices in which carbon dioxide is used as a refrigerant are not regarded to be in widespread use at present, and there is little demand to reduce the time required to perform the refrigerant charging task to facilitate mass production, even in manufacturing plants.
- However, should such hot-water-supplying devices come into more widespread use, issues concerning their efficiency will arise.
- Currently, in office air conditioners and other equipment in which fluorocarbons are used as refrigerants, interconnecting refrigerant piping for connecting the indoor and outdoor units is fitted on-site in the building in which the air conditioners are to be installed, and often the refrigerant charging task is performed on-site. Even in cases in which the indoor and outdoor air conditioning machines have been charged in advance with a predetermined
amount of refrigerant, additional refrigerant charging tasks will be performed on site, depending on the length of the interconnecting refrigerant piping that has been fitted on-site, as well as other factors. In on-site refrigerant charging tasks, a method is adopted in which the space inside the piping is evacuated using a vacuum pump or the like, and a refrigerant is delivered from a cylinder into the piping. - However, when the on-site refrigerant charging task involves using the same procedure for conventional chlorofluorocarbons but for a carbon dioxide refrigerant, there will be incidences of faults related to, e.g., an increase in the time required for the task, or an inability for the air conditioning operation to commence for a certain period of time after charging is completed.
- An object of the present invention is to provide a refrigerant charging method for a refrigeration device in which carbon dioxide is used as a refrigerant, wherein it is possible to reduce the time required for refrigerant charging and the time between refrigerant charging and recommencing operation.
- Refrigerant charging methods according to
claims 1 and 4 are alternatively provided. - A refrigerant charging method according to a first aspect is a refrigerant charging method used when a refrigeration device having an indoor unit and an outdoor unit and having carbon dioxide used as a refrigerant is installed on-site, the indoor unit and the outdoor unit are connected using interconnecting piping, and the refrigerant is subsequently charged on-site into the refrigeration device. The refrigerant charging method comprises a connecting step and a refrigerant charging step. In the connecting step, a container containing the refrigerant is connected to a space in the refrigeration device that is intended to be charged by refrigerant, heating means being interposed therebetween. In the refrigerant charging step, the refrigerant is moved from the container to the intended charging space that is substantially in a vacuum state, via the heating means. In the refrigerant charging step, furthermore, the refrigerant that has exited the container is heated by the heating means so that a specific enthalpy of the refrigerant when entering the intended charging space will be 430 kJ/kg or higher.
- Refrigeration devices such as a hot-water-supplying device having a refrigeration cycle in which a carbon dioxide refrigerant is used are currently charged with the refrigerant at a manufacturing plant or another production site belonging to a manufacturer. However, refrigeration devices such as office air conditioners are not charged with carbon dioxide refrigerant at the locations at which the devices are installed. In other words, at present, carbon dioxide refrigerants are only widely used in refrigeration devices that are not charged at the installation location; the only refrigeration devices sold commercially have been completely charged with the refrigerant at the manufacturing site.
- However, the refrigerant charging task needs to be optimized and efficient when the use of a carbon dioxide refrigerant is considered for application in office air conditioners or other refrigeration devices where it is common for interconnecting refrigerant piping for connecting indoor and outdoor units to be fitted in the buildings where the device is installed, and charging of the refrigerant to be performed on-site.
- Therefore, the present inventors conducted a variety of investigations into charging refrigeration devices with a carbon dioxide refrigerant. First, when the refrigerant is to be charged into the intended charging space of a refrigeration device having carbon dioxide as a refrigerant, and the temperature of a cylinder for discharging and supplying the refrigerant exceeds 31°C, the carbon dioxide refrigerant inside the cylinder will reach a supercritical state. When the refrigerant starts to be supplied from the cylinder into the intended charging space, which is substantially in a vacuum state, then in some instances the amount of heat held by the refrigerant will cause the pressure to decrease sharply, whereby the refrigerant will change into a "dry ice" state (solid state). Specifically, when the specific enthalpy of the refrigerant when entering the intended charging space is less than 430 kJ/kg, an abrupt drop in the pressure can cause the refrigerant to change to a solid state. If the refrigerant changes to a solid state while in the intended charging space, the trailing refrigerant flowing into the space will be obstructed by the solidified refrigerant and the time until the charging is completed will increase, or more time will elapse after charging until the operation can recommence (until the solid state refrigerant dissolves).
- In order to solve the aforedescribed problems, according to the refrigerant charging method of the first aspect, heating means is provided between a refrigerant container and the space intended to be charged by the refrigerant, and the refrigerant is heated using the heating means, causing the specific enthalpy of the refrigerant to be 430 kJ/kg or higher when it enters the intended charging space. According to this method, even if the refrigerant inside the high-temperature cylinder is in a supercritical state, it is possible to prevent the refrigerant changing into a solid state during the charging process due to the pressure sharply decreasing, and to minimize the incidence of faults related to, e.g., the solid-state refrigerant (dry ice) becoming an obstruction, as well as an increase in the charging time or the time following refrigerant charging until operation recommences.
- A refrigerant charging method according to a second aspect is a refrigerant charging method for a refrigeration device in which carbon dioxide is used as a refrigerant, the method comprising a connecting step and a refrigerant charging step. In the connecting step, a container containing the refrigerant is connected to a space in the refrigeration device that is intended to be charged by refrigerant, heating means being interposed therebetween. In the refrigerant charging step, the refrigerant is moved from the container to the intended charging space that is substantially in a vacuum state, via the heating means. In the refrigerant charging step, furthermore, the refrigerant that has exited the container is heated by the heating means so that a specific enthalpy of the refrigerant when entering the intended charging space will be 430 kJ/kg or higher.
- Refrigeration devices such as a hot-water-supplying device having a refrigeration cycle in which a carbon dioxide refrigerant is used are currently charged with the refrigerant at a manufacturing plant belonging to a manufacturer. However, refrigeration devices such as office air conditioners are not charged with carbon dioxide refrigerant at the locations at which the devices are installed. In other words, at present, carbon dioxide refrigerants are only widely used in refrigeration devices that are not charged at the installation location; the only refrigeration devices sold commercially have been completely charged with the refrigerant at the manufacturing site. At present, hot-water-supplying devices and other refrigeration devices having carbon dioxide refrigerants are not mass-produced, and there is little demand to reduce the time required to perform the refrigerant charging task to facilitate mass production.
- However, the refrigerant charging task needs to be optimized and efficient in instances such as when the use of a carbon dioxide refrigerant is considered for application in commercial air conditioners or other refrigeration devices where it is common for interconnecting refrigerant piping for connecting indoor and outdoor units to be fitted in the buildings where the device is installed, and charging of the refrigerant to be performed on-site; or when refrigeration devices are mass-produced at a production site.
- Therefore, the present inventors conducted a variety of investigations into charging refrigeration devices with a carbon dioxide refrigerant. First, when the refrigerant is to be charged into the intended charging space of a refrigeration device having carbon dioxide as a refrigerant, in some instances the amount of heat held by the refrigerant will cause the pressure to decrease sharply, whereby the refrigerant will change into a "dry ice" state (solid state). Specifically, when the specific enthalpy of the refrigerant when entering the intended charging space is less than 430 kJ/kg, an abrupt drop in the pressure can cause the refrigerant to change to a solid state. If the refrigerant changes to a solid state while in the intended charging space, the trailing refrigerant flowing into the space will be obstructed by the solidified refrigerant and the time until the charging is completed will increase, or more time will elapse after charging until the operation can recommence (until the solid state refrigerant dissolves).
- In order to solve the aforedescribed problems, according to the refrigerant charging method of the second aspect, heating means is provided between a refrigerant container and the space intended to be charged by the refrigerant, and the refrigerant is heated using the heating means, causing the specific enthalpy of the refrigerant to be 430 kJ/kg or higher when it enters the intended charging space. According to this method, even if the refrigerant inside the high-temperature cylinder is in a supercritical state, it is possible to prevent the refrigerant changing into a solid state during the charging process due to the pressure sharply decreasing, and to minimize the incidence of faults related to, e.g., the solid-state refrigerant (dry ice) becoming an obstruction, as well as an increase in the charging time or the time following refrigerant charging until operation recommences.
- The heating means is a hose or piping connecting a cylinder or other container containing high-pressure refrigerant to a space intended to be charged by the refrigerant in refrigerant piping or another part of a refrigeration device. As long as the heating means can heat the refrigerant that flows therethrough, the heating means may be piping having an attached heater, or an uninsulated hose or piping through which the heat of the outside air is transferred to the refrigerant. Having the hose connecting the cylinder or other container and the space intended to be charged by the refrigerant extended but kept free of insulation makes it possible for the hose to be used as the heating means, as is particularly so in an environment where the temperature of the surrounding atmosphere exceeds 31°C, which is the critical temperature of carbon dioxide.
- The refrigerant charging method according to a third aspect is the method of the first and second aspects, wherein in the refrigerant charging step, the refrigerant that has exited the container is heated by the heating means so that the temperature and pressure of the refrigerant when entering the intended charging space will be values that exceed those on a boundary line passing through
points 1 to 5. The first point is the point at a temperature of 0°C and a pressure of 3.49 MPa, the second point is the point at a temperature of 10°C and a pressure of 4.24 MPa, the third point is the point at a temperature of 20°C and a pressure of 5.07 MPa, the fourth point is the point at a temperature of 30°C and a pressure of 6.00 MPa, and the fifth point is the point at a temperature of 40°C and a pressure of 7.06 MPa. - The refrigerant that has exited the container is heated by the heating means so that the temperature and pressure of the refrigerant when entering the intended charging space will be values that exceed those on the boundary line passing through
points 1 to 5. Therefore, the specific enthalpy of the refrigerant when entering the intended charging space will be 430 kJ/kg or higher, and the refrigerant will not change to a solid state while in the space targeted for charging by refrigerant. - A refrigerant charging method according to a fourth aspect is a refrigerant charging method used when a refrigeration device having an indoor unit and an outdoor unit and having carbon dioxide used as a refrigerant is installed on-site, the indoor unit and the outdoor unit are connected using interconnecting piping, and the refrigerant is subsequently charged on-site into the refrigeration device. The refrigerant charging method comprises a cooling step and a refrigerant charging step. In the cooling step, a container that contains the refrigerant and supplies the refrigerant to the space in the refrigeration device intended to be charged by the refrigerant is cooled to 31°C or below. In the refrigerant charging step, the refrigerant is moved to the intended charging space that is substantially in a vacuum state from the container that has reached 31°C or below via the cooling step. In the refrigerant charging step, first, the refrigerant that is in a gas phase within the container is moved into the intended charging space, whereupon the refrigerant that is in a liquid phase within the container is moved into intended charging space.
- Refrigeration devices such as a hot-water-supplying device having a refrigeration cycle in which a carbon dioxide refrigerant is used are currently charged with the refrigerant at a manufacturing plant belonging to a manufacturer. However, refrigeration devices such as office air conditioners are not charged with carbon dioxide refrigerant at the locations at which the devices are installed. In other words, at present, carbon dioxide refrigerants are only widely used in refrigeration devices that are not charged at the installation location; the only refrigeration devices sold commercially have been completely charged with the refrigerant at the manufacturing site.
- However, the refrigerant charging task needs to be optimized and efficient when the use of a carbon dioxide refrigerant is considered for application in refrigeration devices such as commercial air conditioners where it is common for interconnecting refrigerant piping for connecting indoor and outdoor units to be fitted in the buildings where the device is installed, and charging of the refrigerant to be performed on-site.
- Therefore, the present inventors conducted a variety of investigations into charging refrigeration devices with a carbon dioxide refrigerant. First, when the refrigerant is to be charged into the intended charging space of a refrigeration device having carbon dioxide as a refrigerant, and when the refrigerant starts to be supplied from the cylinder into the intended charging space, which is in substantially a vacuum state, then in some instances the amount of heat held by the refrigerant will cause the pressure to decrease sharply, whereby the refrigerant will change into a "dry ice" state (solid state). If the refrigerant changes to a solid state while in the intended charging space, the trailing refrigerant flowing into the space will be obstructed by the solidified refrigerant and the time until the charging is completed will increase, or more time will elapse after charging until the operation can recommence (until the solid state refrigerant dissolves).
- In order to solve the aforedescribed problems, according to the refrigerant charging method of the fourth aspect, a cooling step is provided before the refrigerant charging step. In the cooling step, a container that supplies the refrigerant to the space in the refrigeration device intended to be charged by the refrigerant is cooled to 31°C or below. As a result, the refrigerant inside the cylinder will not reach the supercritical state, and will be in a liquid phase or gas phase. Moreover, the refrigerant that is in a gas phase inside the container will first be caused to move into the space intended to be charged by the refrigerant; therefore, it will be substantially impossible for the refrigerant to change to the solid state even if the intended charging space is in a vacuum state and the refrigerant experiences an abrupt drop in pressure. Refrigerant that is in a liquid phase will similarly not change to a solid state in the intended charging space because the refrigerant that is in a liquid phase inside the cylinder will enter the intended charging space after the refrigerant that is in a gas phase inside the container has entered the intended charging space and the pressure therein has risen to some extent.
- Thus, according to the refrigerant charging method of the fourth aspect, it is possible to prevent the incidence of circumstances under which refrigerant that has entered the intended charging space from the container changes into a solid state during the charging process, and to minimize the incidence of faults related to, e.g., the solid-state refrigerant becoming an obstruction, as well as an increase in the charging time or the time following refrigerant charging until operation recommences.
- The refrigerant charging method according to a fifth aspect is a refrigerant charging method for a refrigeration device in which carbon dioxide is used as a refrigerant, and comprises a cooling step and a refrigerant charging step. In the cooling step, a container that contains the refrigerant and supplies the refrigerant to a space in the refrigeration device intended to be charged by the refrigerant is cooled to 31°C or below. In the refrigerant charging step, the refrigerant is moved to the intended charging space that is substantially in a vacuum state from the container that has reached 31°C or below via the cooling step. In the refrigerant charging step, first, the refrigerant that is in a gas phase within the container is moved into the intended charging space, whereupon the refrigerant that is in a liquid phase within the container is moved into the intended charging space.
- Refrigeration devices such as a hot-water-supplying device having a refrigeration cycle in which a carbon dioxide refrigerant is used are currently charged with the refrigerant at a manufacturing plant or another production site belonging to a manufacturer. However, refrigeration devices such as office air conditioners are not charged with carbon dioxide refrigerant at the locations at which the devices are installed. In other words, at present, carbon dioxide refrigerants are only widely used in refrigeration devices that are not charged at the installation location; the only refrigeration devices sold commercially have been completely charged with the refrigerant at the manufacturing site. At present, refrigeration devices having carbon dioxide refrigerants such as hot-water-supplying devices are not mass-produced, and there is little demand to reduce the time required to perform the refrigerant charging task to facilitate mass production.
- However, the refrigerant charging task needs to be optimized and efficient in such instances as when the use of a carbon dioxide refrigerant is considered for application in office air conditioners or other refrigeration devices where it is common for interconnecting refrigerant piping for connecting indoor and outdoor units to be fitted in the buildings where the device is installed, and charging of the refrigerant to be performed on-site; or when refrigeration devices are mass-produced at a production site.
- Therefore, the present inventors conducted a variety of investigations into charging refrigeration devices with a carbon dioxide refrigerant. First, when the refrigerant is to be charged into the intended charging space of a refrigeration device having carbon dioxide as a refrigerant, and when the refrigerant starts to be supplied from the cylinder into the intended charging space, which is in substantially a vacuum state, then in some instances the amount of heat held by the refrigerant will cause the pressure to decrease sharply, whereby the refrigerant will change into a "dry ice" state (solid state). If the refrigerant changes to a solid state while in the intended charging space, the trailing refrigerant flowing into the intended charging space will be obstructed by the solidified refrigerant and the time until the charging is completed will increase, or more time will elapse after charging until the operation can recommence (until the solid state refrigerant dissolves).
- In order to solve the aforedescribed problems, according to the refrigerant charging method of the fifth aspect, a cooling step is provided before the refrigerant charging step. In the cooling step, a container that supplies the refrigerant to the space in the refrigeration device intended to be charged by the refrigerant is cooled to 31°C or below. As a result, the refrigerant inside the cylinder will not reach the supercritical state, and will be in a liquid phase or gas phase. Moreover, the refrigerant that is in a gas phase inside the container will first be caused to move into the space intended to be charged by the refrigerant; therefore, it will be substantially impossible for the refrigerant to change to the solid state even if the intended charging space is in a vacuum state and the refrigerant experiences an abrupt drop in pressure. Refrigerant that is in a liquid phase will similarly not change to a solid state in the space intended to be charged by the refrigerant because the refrigerant that is in a liquid phase inside the cylinder will enter the intended charging space after the refrigerant that is in a gas phase inside the container has entered the intended charging space and the pressure therein has risen to some extent.
- Thus, according to the refrigerant charging method of the fifth aspect, it is possible to prevent the incidence of circumstances under which refrigerant that has entered the intended charging space from the container changes into a solid state during the charging process, and to minimize the incidence of faults related to, e.g., the solid-state refrigerant becoming an obstruction, as well as an increase in the charging time or the time following refrigerant charging until operation recommences.
- In the cooling step, the container may be cooled using cooling water, or, when the surrounding atmospheric temperature is low, the container may be cooled using ambient air (including the time until the container reaches 31°C or lower)
- According to the refrigerant charging method of the first to third aspects, even if the refrigerant inside the high-temperature cylinder is in a supercritical state, it is possible to prevent the refrigerant changing into a solid state during the charging process due to the pressure sharply decreasing, and to minimize the incidence of faults related to, e.g., the solid-state refrigerant becoming an obstruction, as well as an increase in the charging time or the time following refrigerant charging until operation recommences.
- According to the refrigerant charging method of the fourth and fifth aspects, it is possible to prevent the incidence of circumstances under which refrigerant that has entered the intended charging space from the container changes into a solid state during the charging process, and to minimize the incidence of faults related to, e.g., the solid-state refrigerant becoming an obstruction, as well as an increase in the charging time or the time following refrigerant charging until operation recommences.
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FIG. 1 is a diagram showing a refrigeration cycle of an air conditioning device. -
FIG. 2 is a simplified schematic diagram showing pressure and enthalpy states of a CO2 refrigerant. -
FIG. 3 is a diagram showing a state wherein a refrigerant charging cylinder is connected to the refrigeration cycle of the air conditioning device. -
FIG. 4 is a detailed diagram showing pressure and enthalpy states of a CO2 refrigerant (created with reference to Fundamentals: 2005 ASHRAE Handbook: SI Edition). -
- 6, 7
- Interconnecting refrigerant piping (space targeted for charging by refrigerant)
- 10
- Air conditioning device
- 20
- Outdoor unit
- 50
- Indoor unit (space targeted for charging by refrigerant)
- 81
- Cylinder (container)
- 83
- Heater (heating means)
- In a refrigeration cycle having carbon dioxide used as a refrigerant, the refrigerant charging method according to the present invention is a method for supplying the refrigerant from a cylinder or another container in which the refrigerant is contained to a space intended to be charged by the refrigerant within the refrigeration cycle, and for efficiently charging the intended charging space with the necessary amount of refrigerant. First, a brief description shall be provided of the refrigeration cycle to be charged with refrigerant using the refrigerant charging method, after which a description shall be provided of a refrigerant charging method according to a first embodiment and a refrigerant charging method according to a second embodiment.
-
FIG. 1 is drawing of a refrigeration cycle of anair conditioning device 10 in which carbon dioxide is used as a refrigerant (hereinafter referred to as CO2 refrigerant). Theair conditioning device 10 is a multiple-unit air conditioning device installed in an office building or similar structure, and is used for cooling or heating a plurality of spaces, the device having a plurality ofindoor units 50 linked to a singleoutdoor unit 20. Theair conditioning device 10 comprises theoutdoor unit 20, the plurality ofindoor units 50, and interconnectingrefrigerant piping 6, 7 for connecting theunits outdoor unit 20 has acompressor 21, a four-way switching valve 22, anoutdoor heat exchanger 23, anoutdoor expansion valve 24, closingvalves indoor units 50 has anindoor expansion valve 51 and anindoor heat exchanger 52, is installed in the ceiling or other region of each open space (rooms or the like) inside the building, and is connected to the outdoor unit via the interconnectingrefrigerant piping 6, 7, which are fitted on-site. Fitting the piping on-site to theoutdoor unit 20 and theindoor units 50 brought into the building thus forms a single refrigeration cycle. - As shown in
FIG. 1 , the refrigeration cycle of theair conditioning device 10 is a closed circuit in which thecompressor 21, the four-way switching valve 22, theoutdoor heat exchanger 23, theoutdoor expansion valve 24, eachindoor expansion valve 51, and eachindoor heat exchanger 52 are linked by refrigerant piping that includes the interconnectingrefrigerant piping 6, 7. After the refrigeration cycle has been formed on-site, CO2 refrigerant is discharged and supplied from a cylinder to a space within theindoor units 50 and the interconnecting refrigerant piping 6, 7 (the space intended to be charged by the refrigerant). The refrigerant charging task will be described in more detail hereinafter. - When the refrigerant charging task has been completed and the refrigeration cycle has been charged with the necessary amount of CO2 refrigerant, the
air conditioning device 10 reaches a state in which heat exchange is performed between the CO2 refrigerant flowing through theindoor heat exchangers 52 of theindoor units 50, and the air inside the rooms, whereby an air conditioning operation for cooling or heating the spaces inside the building can be performed. - The four-
way switching valve 22 in theair conditioning device 10 is used to switch the direction in which the refrigerant flows, thereby making it possible to switch between a heating operation and a cooling operation. - During the cooling operation, the
outdoor heat exchanger 23 becomes a gas cooler, and theindoor heat exchangers 52 become evaporators. During the heating operation, theoutdoor heat exchanger 23 becomes an evaporator, and theindoor heat exchangers 52 become gas coolers. - In
FIG. 1 , point A is an inlet side of thecompressor 21 during the heating operation, and point B is a discharge side of thecompressor 21 during the heating operation. Point C is a refrigerant outlet of theindoor heat exchangers 52 during the heating operation, and point D is a refrigerant entrance of theoutdoor heat exchanger 23 during the heating operation. -
FIG. 2 is a diagram used to express a pressure-enthalpy state of the CO2 refrigerant in a simplified manner, wherein the vertical axis shows the pressure and the horizontal axis shows the enthalpy. Tcp is a constant temperature line that passes through a critical point CP. In the region that is to the right of the isotherm Tcp and is at or above the critical pressure, which is the pressure at the critical point CP, the CO2 refrigerant enters a supercritical state, wherein the CO2 refrigerant becomes a fluid simultaneously exhibiting diffusibility, which is a characteristic of a gas, and solubility, which is a characteristic of a liquid. Theair conditioning device 10 operates using a refrigeration cycle that includes the supercritical state, as shown by the bold line inFIG. 2 . In the refrigeration cycle for the heating operation, the CO2 refrigerant is compressed by thecompressor 21 up to a pressure that exceeds the critical pressure, cooled to a liquid by theindoor heat exchanger 52, decompressed at theoutdoor expansion valve 24, evaporated in theoutdoor heat exchanger 23, becomes a gas, and is once more drawn into thecompressor 21. - The
outdoor unit 20 and theindoor units 50 are connected using the interconnectingrefrigerant piping 6, 7, which is fitted on-site. After a single closed refrigeration cycle has been formed therefrom, the refrigerant charging task is performed. - In the refrigerant charging method according to the first embodiment, first, the interior of the
indoor units 50 and the interconnectingrefrigerant piping 6, 7 is evacuated (brought to extremely low pressure) using a vacuum pump or the like (not shown). Next, as shown inFIG. 3 , acylinder 81 containing CO2 refrigerant is connected to a charge port installed near the closingvalve 26 of theoutdoor unit 20. There is attached to the piping connecting thecylinder 81 and the charge port aheater 83 for heating the piping and the CO2 refrigerant that flows through the interior thereof. Next, theheater 83 is activated so that the specific enthalpy of the CO2 refrigerant having entered the interconnecting refrigerant piping 7 from the charge port will reach 430 kJ/kg or higher, and refrigerant charging will be performed. Specifically, theheater 83 is activated so that the temperature and pressure of the CO2 refrigerant having entered the interconnectingrefrigerant piping 7 will fall in the area on the higher [value] side of the line connecting the five points PI to P5 shown inFIG. 4 . Point PI is the point at a temperature of 0°C and a pressure of 3.49 MPa, point 2 is the point at a temperature of 10°C and a pressure of 4.24 MPa, point 3 is the point at a temperature of 20°C and a pressure of 5.07 MPa, point 4 is the point at a temperature of 30°C and a pressure of 6.00 MPa, and point 5 is the point at a temperature of 40°C and a pressure of 7.06 MPa. - Thus, when the refrigerant charging task is initiated, there will be no incidence of any fault related to, the CO2 refrigerant in the interconnecting
refrigerant piping 7 changing to a solid and obstructing the flow of the trailing CO2 refrigerant. - Specifically, as shown in the pressure-enthalpy state diagram for carbon dioxide shown in
FIGS. 2 and4 , when the specific enthalpy is less than 430 kJ/kg, the CO2 refrigerant in the state recorded on the right side of the isotherm Tcp that passes through the critical point CP of carbon dioxide (critical temperature: approximately 31°C, critical pressure: approximately 7.3 MPa) will shift to the shaded area inFIG. 2 (inFIG. 4 , the area in which the pressure is at or below approximately 0.5 MPa and the specific enthalpy is less than 430 kJ/kg) when an abrupt drop in pressure occurs, and will change to a solid state. In order to prevent this, the CO2 refrigerant that has exited thecylinder 81 is heated by theheater 83 so that the specific enthalpy of the CO2 refrigerant will reach 430 kJ/kg or higher. As a result, no matter how abruptly the pressure may drop when the CO2 refrigerant enters the interconnectingrefrigerant piping 7, the CO2 refrigerant will not change to a solid state, because as long as the specific enthalpy is 430 kJ/kg or higher, carbon dioxide will not change to a solid (seeFIG. 4 ). - As described above, in the refrigerant charging method according to the first embodiment, the specific enthalpy of the CO2 refrigerant is brought to 430 kJ/kg or higher at the time the CO2 refrigerant enters the evacuated space intended to be charged (the interior space of the
indoor units 50 and the interconnecting refrigerant piping 6, 7), there will be no incidence of faults related to, e.g., the CO2 refrigerant in the interconnectingrefrigerant piping 7 changing to a solid near the charge port and obstructing the flow of the trailing CO2 refrigerant, or long periods of time elapsing after charging until theair conditioning device 10 can be operated. - In the abovedescribed refrigerant charging method, a
heater 83 is attached to the piping between thecylinder 81 and the charge port; however, in place of installing theheater 83, it is possible to adopt a method involving lengthening the piping between thecylinder 81 and the charge port. It is possible for the long piping between thecylinder 81 and the charge port to not have an insulation material or the like wrapped therearound, and for heat in the air surrounding to be used to heat the CO2 refrigerant flowing through the piping. Even in such cases, as long as the specific enthalpy of the CO2 refrigerant when the CO2 refrigerant enters the intended charging space can be kept in a state of being 430 kJ/kg or higher, there will be no incidence of faults related to, e.g., the CO2 refrigerant changing to a solid near the charge port and obstructing the flow of the trailing CO2 refrigerant, or long periods of time elapsing after charging until theair conditioning device 10 can be operated. - The
outdoor unit 20 and theindoor units 50 are connected using the interconnectingrefrigerant piping 6, 7, which is fitted on-site. After a single closed refrigeration cycle has been formed therefrom, the refrigerant charging task is performed. A description will be given with reference toFIG. 3 ; however, in a case in which the refrigerant charging method according to a second embodiment is employed, theheater 83 shown inFIG. 3 will be unnecessary. - In the refrigerant charging method according to the second embodiment, first, the interiors of the
indoor units 50 and the interconnectingrefrigerant piping 6,7 are evacuated (brought to extremely low pressure) using a vacuum pump or the like (not shown). Next, acylinder 81 containing CO2 refrigerant is connected to a charge port installed near the closingvalve 26 of theoutdoor unit 20. When thecylinder 81 is at a temperature in excess of 31°C before or after being connected, thecylinder 81 is cooled so as to bring the temperature of the CO2 refrigerant inside thecylinder 81 to 31°C or below. Specifically, thecylinder 81 is cooled using cooling water or another medium (not shown). Once it has been confirmed that the temperature of thecylinder 81 has reached 31°C or below, the CO2 refrigerant in a gas phase (gaseous state) within thecylinder 81 is discharged and supplied into the space intended to be charged by the refrigerant (the space within theindoor unit 50 and the interconnecting refrigerant piping 6, 7). Once the gaseous-state CO2 refrigerant has been supplied, the CO2 refrigerant in a liquid phase (liquid state) within thecylinder 81 is discharged and supplied into the intended charging space. - Thus, when the refrigerant charging task is initiated, there will be no incidence of any fault related to, e.g., the CO2 refrigerant in the interconnecting
refrigerant piping 7 changing to a solid and obstructing the flow of the trailing CO2 refrigerant. - Specifically, as shown in the pressure-enthalpy state diagram for carbon dioxide shown in
FIGS. 2 and4 , when the specific enthalpy is less than 430 kJ/kg, the CO2 refrigerant in the state recorded on the right side of the isotherm Tcp that passes through the critical point CP of carbon dioxide (critical temperature: approximately 31°C, critical pressure: approximately 7.3 MPa) will shift to the shaded area inFIG. 2 (inFIG. 4 , the area in which the pressure is at or below approximately 0.5 MPa and the specific enthalpy is less than 430 kJ/kg) when an abrupt drop in pressure occurs, and will change to a solid state. In order to prevent such a change, therefore, thecylinder 81 is cooled to 31°C or below, before refrigerant charging is performed. As a result, the refrigerant inside thecylinder 81 will not reach the supercritical state, and will be in a liquid phase or gas phase. Moreover, the CO2 refrigerant that is in a gas phase inside thecontainer 81 will first be caused to move into the space intended to be charged by the refrigerant; therefore, it will be substantially impossible for the refrigerant to change to the solid state even if the intended charging space is in a vacuum state and the CO2 refrigerant experiences an abrupt drop in pressure. CO2 refrigerant that is in a liquid phase will similarly not change to a solid state in the space intended to be charged by the refrigerant because the refrigerant that is in a liquid phase inside thecylinder 81 will enter the intended charging space after the CO2 refrigerant that is in a gas phase inside thecylinder 81 has entered the space and the pressure therein has risen to some extent. - As described above, in the refrigerant charging method according to the second embodiment, there will be substantially no incidence of any fault related to, e.g., the CO2 refrigerant changing to a solid near the charge port and obstructing the flow of the trailing CO2 refrigerant, or long periods of time elapsing after charging until the
air conditioning device 10 can be operated. - In the abovedescribed refrigerant charging method, cold water or another medium is used for cooling the
cylinder 81; however, when the atmospheric temperature surrounding thecylinder 81 is low, it is possible to employ a method involving waiting for the temperature of thecylinder 81 to unassistedly reach 31°C or below. In this case as well, the temperature of the CO2 refrigerant inside thecylinder 81 decreases, and as long as the CO2 refrigerant that is in a gas phase discharges first among the liquid- and gas-phase CO2 refrigerant into the space intended to be charged by the refrigerant, there will be substantially no incidence of any fault related to, e.g., the CO2 refrigerant changing to a solid near the charge port and obstructing the flow of the trailing CO2 refrigerant, or long periods of time elapsing after charging until theair conditioning device 10 can be operated. -
- (1)
In the abovementionedair conditioning device 10, theoutdoor unit 20 that is charged in advance with CO2 refrigerant at the manufacturing plant or another production site belonging to a manufacturer is brought on-site (to the building), and the refrigerant is charged into the space within theindoor units 50 and the interconnectingrefrigerant piping 6, 7 on-site. However, it is also possible to use the refrigerant charging method according to the present invention in cases in which all of the refrigerant charging is performed on-site. It is also possible to use the refrigerant charging method according to the present invention when theoutdoor unit 20 is charged with refrigerant at the manufacturing plant or other production site. - (2)
It is also possible to use the refrigerant charging method according to the present invention for refrigeration devices other than the multi-split typeair conditioning device 10. For example, using the refrigerant charging method according to the present invention makes it possible to reduce the amount of time necessary for the refrigerant charging task even in heat pump hot-water-supplying devices in which the refrigeration cycle is completed and also the refrigerant is charged in a manufacturing plant or another production site belonging to a manufacturer.
Claims (5)
- A refrigerant charging method for a refrigeration device (10) in which carbon dioxide is used as a refrigerant, comprising:a connecting step for connecting a container (81) containing the refrigerant into a space in the refrigeration device that is intended to be charged by the refrigerant, and a refrigerant charging step for moving refrigerant from the container to the intended space,characterised in that heating means (83) is interposed between the container (81) and the intended charging space, wherein in the refrigerant charging step, the refrigerant moves to the intended charging space that is substantially in a vacuum state, via the heating means;the refrigerant that has exited the container is heated by the heating means so that a specific enthalpy of the refrigerant when entering the intended charging space will be 430 kJ/kg or higher.
- The refrigerant charging method of claim 1, which is used when the refrigeration device (10) having an indoor unit (50) and an outdoor unit (20) is installed on-site, the indoor unit and the outdoor unit are connected using interconnecting piping (6, 7), and the refrigerant is subsequently charged on-site into the refrigeration device (10).
- The refrigerant charging method of claim 1 or claim 2, wherein
in the refrigerant charging step, the refrigerant that has exited the container is heated by the heating means so that the temperature and pressure of the refrigerant when entering the intended charging space will be values that exceed those on a boundary line passing through a first point at a temperature of 0°C and a pressure of 3.49 MPa, a second point at a temperature of 10°C and a pressure of 4.24 MPa, a third point at a temperature of 20°C and a pressure of 5.07 MPa, a fourth point at a temperature of 30°C and a pressure of 6.00 MPa, and a fifth point at a temperature of 40°C and a pressure of 7.06 MPa. - A refrigerant charging method for a refrigeration device (10) in which carbon dioxide is used as a refrigerant;
the refrigerant charging method comprising:a cooling step for cooling a container (81), the container (81) containing the refrigerant and supplying the refrigerant to a space in the refrigeration device intended to be charged by the refrigerant; anda refrigerant charging step for moving the refrigerant to the intended charging space,characterised in that in the cooling step, the container is cooled to 31 °C or below, and in the refrigerant charging step, the refrigerant moves to the intended charging space, that is substantially in a vacuum state from the container that has reached 31 °C or below via the cooling step; whereinin the refrigerant charging step, first, refrigerant that is in a gas phase within the container is moved into the intended charging space, whereupon refrigerant that is in a liquid phase within the container is moved into the intended charging space. - The refrigerant charging method of claim 4, which is used when the refrigeration device (10) having an indoor unit (50) and an outdoor unit (20) is installed on-site, the indoor unit and the outdoor unit are connected using interconnecting piping (6, 7), and the refrigerant is subsequently charged on-site into the refrigeration device (10).
Applications Claiming Priority (2)
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JP2006199707A JP5336039B2 (en) | 2006-07-21 | 2006-07-21 | Refrigerant charging method in refrigeration apparatus using carbon dioxide as refrigerant |
PCT/JP2007/064187 WO2008010519A1 (en) | 2006-07-21 | 2007-07-18 | Refrigerant loading method for refrigeration device using carbon dioxide as refrigerant |
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EP2051028A1 EP2051028A1 (en) | 2009-04-22 |
EP2051028A4 EP2051028A4 (en) | 2014-06-25 |
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EP07790941.4A Active EP2051028B1 (en) | 2006-07-21 | 2007-07-18 | Refrigerant loading method for refrigeration device using carbon dioxide as refrigerant |
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EP (1) | EP2051028B1 (en) |
JP (1) | JP5336039B2 (en) |
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ES (1) | ES2720323T3 (en) |
TR (1) | TR201905061T4 (en) |
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KR20110032006A (en) | 2011-03-29 |
US8479526B2 (en) | 2013-07-09 |
CN102645063B (en) | 2014-03-05 |
EP2051028A4 (en) | 2014-06-25 |
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US20130219928A1 (en) | 2013-08-29 |
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JP5336039B2 (en) | 2013-11-06 |
CN101490484A (en) | 2009-07-22 |
AU2007276161B2 (en) | 2010-07-29 |
CN102645063A (en) | 2012-08-22 |
WO2008010519A1 (en) | 2008-01-24 |
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AU2007276161A1 (en) | 2008-01-24 |
ES2720323T3 (en) | 2019-07-19 |
US9869498B2 (en) | 2018-01-16 |
TR201905061T4 (en) | 2019-05-21 |
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KR101123240B1 (en) | 2012-03-22 |
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